PHOTOS: Obama in Chicago

Mac complained of having a cold and a doctor at Northwestern gave him a shot for it, he said.

Earles said he thought Mac was having a negative reaction to the injection and gave him medications to counteract it. He called up the other doctor, who told him Mac was diagnosed with pneumonia in both lungs. That doctor either at or affiliated with Northwestern Memorial Hospital thought Mac checked himself in.

PHOTOS: Jonas Brothers in Chicago

Earles said he immediately got Mac up, so he could go to the hospital. The comedian walked out to a vehicle with a chauffeur waiting to drive him there, he said.

Mac died from complications related to pneumonia three weeks later at the age of 50.